1. Field of the Invention
The present invention relates to an enclosed high voltage compressed gas circuit breaker of the type which is enclosed in an elongated casing filled with compressed gas, preferably sulphur hexafluoride, comprising a high-pressure chamber and a low-pressure chamber, and with at least one movable contact and a blast valve.
The operating device for the contact and/or the blast valve comprises a driving means, which is operated by compressed gas and alternatively connectable to the high-pressure chamber and the low-pressure chamber by way of a compressed gas valve. This gas valve contains a movable valve member, which in one of its end positions seals against a valve seat arranged around a connection opening to said high-pressure chamber, and with at least part of its side-- facing away from said connection opening-- limits a space permanently communicating with the high-pressure chamber.
2. The Prior Art
For operation of compressed gas circuit breakers it is previously known (for example from U.S. Pat. Nos. 3,498,331 to Grune and 3,715,542 to Grune et al) to use a compressed gas valve, in which the movable valve member is constructed so that both sides of the member are permanently affected by the compressed gas. This results in the advantage that the force required for opening the valve can be considerably reduced. In the known constructions, however, the members for operating the valve are either constructed integrally with the movable valve member, which leads to a larger movable mass and thus to longer operating times, or they are built into the valve housing itself, which lessens the accessibility for control and service, in particular in the case of sulphur hexafluoride circuit breakers.